Answer:
They drove 81 miles
Step-by-step explanation:
Total cost = fees per day * days + miles * mileage charge
We know the total cost = 117.15
We know it was 3 days at 35/day
The mileage charge is .15 per mile
117.15 = 35*3 + m*.15
Multiplying
117.15 = 105+.15m
Subtract 105 from each side
117.15-105 = 105-105 +.15m
12.15 = .15m
Divide by .15 on each side
12.15 /.15 =.15m/.15
81 = m
They drove 81 miles